Benzodiazepines and discrimination behaviour: dissociation of response and sensory factors.

Ten London pigeons were trained on a schedule which allowed concurrent measurement of motor and exteroceptive sensory changes. The task involved a conditional colour discrimination contingent upon the completion of a fixed interval schedule of responding. As a preliminary pharmacological study the effects of the benzodiazepines, chlordiazepoxide and flurazepam were investigated. Both drugs enhanced perseverative responding (after completion of the FI), and to a variable degree responding during the FI, although there was no evidence for an increase in responding during the inter-trial-intervals. On the other hand, no marked changes in discrimination performance were observed. It is concluded that the most significant effects of these benzodiazepines are on motor mechanisms.